Foamed beverages such as espresso, cappuccino and latte prepared from a single serve capsule are becoming more and more popular. The principle of using pre-metered and pre-packed portions of coffee or the like for the preparation of coffee or other beverages has already existed for a long time. It has the advantage that it facilitates the preparation of coffee while ensuring that the quality of the product remains relatively consistent. It also provides more convenience for the operator. The capsule usually sits in a leak-tight enclosure of a coffee-type machine and hot water is passed through the capsule under pressure. The use of roast-and-ground powder is widely utilized commercially in capsules that perforate under the build-up of pressure to release the extracted liquid. However, to date, there do not exist any systems of capsules adapted for soluble powder that would confer a sufficient level of quality and foam able to compete with the roast-and-ground segment on the market. Therefore, all the attempts for such soluble powder containing capsules have not met with commercial success to date.
A problem commonly met with the existing capsules comes from the fact that the pressure cannot build up sufficiently well to have the powder entirely and homogeneously mixed with water. Channeling problems are usually noticed within the powder cake causing primary paths for water and zones which are not properly wetted by water. Therefore, the capsule can usually not be fully emptied or washed causing inconsistent dosage and powder waste left within the capsule. Other common problems met with the existing capsules relate to the generation of a poor foam or even no foam at all thereby producing beverages such as cappuccino or latte of very poor quality. As a result, these poor quality beverages get very little consumer acceptance.
Those problems are dependent upon the way the pressure builds up inside the capsule and the way the beverage is released into the cup. The building-up of the pressure and release are steps to ensure a product of satisfactory quality as well as to ensure a correct emptying or washing of the product inside the capsule.
Another problem results from the intensive mechanical interactions between the capsule and the means that exert pressure onto the capsule to effect the release of the beverage. Usually, the capsule is perforated by perforated means such as a corrugated or cutting surface or an opening element forcing a passage through the bottom of the capsule and positioning within the capsule. Such interactions have a tendency to generate bits of material from the capsule, such as plastic bits and the like, which may contaminate the beverage.
Foamed beverages such as espresso, cappuccino and latte prepared from dispensing machines are becoming more and more popular. Methods of preparation of such products from a predosed capsule are also known. The principle of using pre-metered and pre-packed portions of coffee and the like for the preparation of coffee-based beverages has the advantages to facilitate the preparation of the beverage while ensuring that the dose-to-dose quality and strength of the beverage remains constant for the same conditions of preparations (dosage, temperature, pressure, time, etc.). It also provides more convenience to the user. The capsule usually sits in a leak-tight enclosure of a special coffee-type machine and hot water is passed through the capsule under pressure. The underside of the capsule perforates under the build-up of pressure to release the extracted liquid. The use of roast-and-ground powder in capsules is commercialized to make coffee cups of high quality.
EP 0 512470 B1 describes a process for extracting sealed cartridges in a cartridge holder in which a mixture of water and air is injected into the cartridge under a pressure of 1 to 20 bar to deform the extraction face. The extraction face of the cartridge is deformed against a relief surface of the cartridge holder comprising relief elements and recessed elements, the extraction face tearing at the location of these relief elements and/or these recessed elements on reaching the breaking stress to enable liquid to be subsequently removed after extraction of the coffee under a pressure of 1 to 20 bar.
This process proves to be very effective for extracting a beverage liquid from an extractable, non-soluble material such as roast and ground coffee. Since the product is not soluble within the cartridge, the bed of material maintains an elevated inside resistance and pressure tends to build up to a relatively high range as more water enters the cartridge. The combination of high pressure, temperature and extraction time is key for extracting the fine aroma compounds from the coffee bed until the extraction face can tear to allow release of the extracted liquid in the cup.
For soluble products, water does not serve to extract solids and coffee aroma compounds but it is supposed to solubilize all the solids. Dilution of the solids is essentially obtained by thorough mixing within the capsule during a sufficient time up to a complete dilution. Furthermore, mixing should be carried out while entrapping sufficient air to form a good foam or froth upon releasing in the cup. Foam generation of soluble powder is complex and may also be dependent on the physical release conditions of the solution through the capsule. These physical conditions involve the level of shear created and pressure release through the openings. The building-up of pressure and the timing for release are also selected to obtain a sufficient mixing and air entrapment in the solution. The problem is that, when liquid starts entering the capsule, the powder starts dissolving and the solution tends to evacuate. As solids content in the capsule decreases, the resistance created by the powder in the capsule decreases proportionally. As a result, the solution tends to evacuate too quickly the capsule and at a too low pressure, without sufficient mixing having been carried out. As mixing is insufficient, lumps may form in the delivered solution, insufficient amount of air is entrapped and the resulting amount of foam created is poor.
U.S. Pat. No. 3,292,527 to Stasse relates to an apparatus and a cartridge adapted to deliver in succession different drinks or beverages without allowing the drink or beverage to contact the basic elements of the apparatus. The cartridge may contain fine soluble powder and has a perforated bottom side that creates a pressure drop capable of retarding the outflow through the orifice. Such a perforated arrangement by itself, even when small, does not produce sufficient shear and does not retain sufficient pressure inside to be capable of generating a properly whipped or foamed beverage.
EP 0 468 080 to Fond also relates to a process of extraction of a cartridge for roast and ground coffee wherein the cartridge has an apertured bottom side to deliver the extracted liquid along an extensive surface. This process is for roast-and-ground but would not properly apply to soluble powder such as instant coffee powder for the same reasons as for U.S. Pat. No. 3,292,527.
WO 01/58786 to Halliday relates to a cartridge for the preparation of whipped beverages of “espresso” type in machines operating at low pressure characterized in that the cartridge incorporates in the beverage flow path, prior to or at the outlet, means for producing a jet of beverage, at least one inlet for air and means to generate a pressure reduction of the jet of beverage whereby in use air from the air inlet is incorporated into the beverage as a plurality of small bubbles. Due to the low pressure inside the cartridge, air must be added by specific air inlets. Such a cartridge specifically involves many parts and, hence, is tricky, complex and expensive to produce.
A need exists for a system to produce a food liquid, such as a coffee-based product, having superior whipped or foam characteristics obtained from a capsule-type system, and for the system to employ a relatively simple and low cost cartridge that can generate a substantially complete dissolution of the soluble food product and a high amount of foam.